Diamond

by
Josh Ashley



Image taken from www.eightstar.com
(Source 1)

    Diamonds have been sought after for years throughout the world for beauty, in both a rough stone picked off the ground or as a finished piece of jewelry. It has been found to have other uses in the industrial world because of its extreme hardness and durability.

Physical and Chemical Properties  *   Geologic Occurrence  *   Diamond Use
Links  *   References Cited  *   About This Page

Physical and Chemical Properties

    Although diamond is usually white or pale yellow, it actually occurs in many colors. It has been found in light shades of red, orange, green, blue, and brown. Deeper shades are rare. Rough diamonds, before the are cut and fashioned, usually have a greasy luster. Once they are cut and polished they have an adamantine luster. Diamond has four directions of cleavage, that are all perfect and create an octahedron. Diamond's octahedron looks like two four sided-pyramids put together at their bases. Diamond can be best distinguished from other minerals by its extremely high hardness, ten on the Mohs Hardness Scale. It is the hardest mineral known to man (Source 2, p. 346). Diamond may be confused with several different minerals in the field, such as quartz and topaz. It can be distinguished by a hardness test, although the test should be more than just trying to scratch glass, because all three can.


Raw diamond octahedron
Image taken from
http://mineral.galleries.com/minerals/elements/diamond/diamond.htm

(Source 3)

    Diamond is in the isometric crystal system (Source 4). It is also entirely composed of carbon. Graphite is also composed of only carbon. Although both diamond and graphite are composed of carbon, they have different structures (i.e., they are polymorphic). Graphite does not have as many covalent bonds as diamond. Each carbon atom in diamond has four covalent bonds to other carbon atoms. In the case of graphite, each carbon atom only has three covalent bonds to other carbon atoms and the atoms of carbon make hexagonal lattice sheets that are held together by Van der Waals bonds (Source 5).

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Geologic Occurrence

    Diamonds have been found in many different localities throughout the world, but there are only a few place that have a notable amounts. Diamonds are found often in alluvial deposits, as this mineral accumulates and weathers well because of its inert chemical nature, extreme hardness, and fairly high specific gravity. Kimberlites or lamproites are the igneous rock types in which diamonds are found in primary deposits. These igneous intrusions are often roughly circular with a pipe-like shape and therefore are often referred to as kimberlite pipes, lamproite pipes, or simply as "diamond pipes." The ratio of diamonds compared with barren rock can be as high as 1:30,000,000 (Source 2, p. 348).


Image taken from
http://www2.cybernex.net/~gemstone/ge10000.html.

(Source 6)

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Diamond Use

    Diamond is one of the most desired gemstones in the world, sought after because of its high hardness, high brilliancy, and its fire. Hardness is related to bonding of the carbon atoms. Brilliancy is a result of index of refraction. Fire is created from diamond's high dispersion. The most valuable diamonds are flawless and completely colorless. A faint yellow color, which is the most common color, detracts from the value. If the diamond occurs in a deep shades of yellow, red, green, or blue, they are known as fancy stones. The Hope Diamond (Source 7) is an example of a famous and valuable deep blue diamond. Diamonds can be artificially colored by radiation, heat, or by being exposed to high speed electrons. These resulting colors can be very hard to distinguish from naturally formed colors. In order to evaluate the quality of diamond, grading scales have been created. Diamonds are graded on what many refer to as the four C's, cut, color, carat, and clarity (Source 8).

    Diamonds also have an important role in industry because of its high hardness. Fragments of diamond crystals are used for cutting glass. The fine powder is used in grinding and polishing other diamonds. Wheels are impregnated with diamonds to be used to cut rocks and other hard minerals. Steel bits are set with diamonds, especially the cryptocrystalline variety called carbonado, for diamond drilling. Diamond is also used in wire drawing and in tools for the truing of grinding wheels.

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Links

To investigate diamond in more detail, visit these links to help make this topic clear as crystal.

1. http://www.diamondcutters.com/diamondhistory.html

2. http://www.pbs.org/wgbh/nova/diamond/textindex.html

3. http://www.diamondfloor.com/

4. http://www.usdiamond.com/

5. http://www.diamond-guide.com/

6. http://www.wehug.com/diamondalert1.html

7. http://www.diamonds.org/education/

8. http://www.helzberg.com/

9. http://catalog.com/vortex/diamond/index.html

10. http://members.aol.com/uglinc/Diamond_Basics.html

11. http://www.diamonds.com/

12. http://www.diamondcutting.net/

13. http://www.web.net/pac/pacnet-l/msg00009.html

14. http://www.geology.neab.net/minerals/diamond.htm

15. http://nmnhwww.si.edu/minsci/hope.htm

16. http://www.gemhut.com/diamond.htm

17. http://www.diamondgrading.com/Articles_Diamond_Glossary.htm

18. http://www.gsf.fi/explor/diamexpl.htm

19. http://www.mnh.si.edu/museum/VirtualTour/Tour/Second/Hope/

20. http://ridge.oce.orst.edu/rkeller/diamonds.html

21. http://www.canabrava.ca/photos.html

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References Cited

1. http://www.eightstar.com

2. Manual of Mineralogy
        Hurlbut, Cornelius S. Jr., and Cornelis Klein. Manual of Mineralogy. New York: John Wiley & Sons, Inc., 1999

3. http://mineral.galleries.com/minerals/elements/diamond/diamond.htm

4. http://www.rockhounds.com/rockshop/xtal/part3.html

5. http://www2.cybernex.net/~gemstone/ge10000.html

6. http://www.chembio.uoguelph.ca/educmat/chm729/band/s5.htm

7. http://nmnhwww.si.edu/minsci/hope.htm

8. http://www.adiamondisforever.com/buy/4cs_nonflash.html

9. Chesterman, Charles W. National Audubon Society Field Guide to North American Rocks and Minerals. New York: Alfred A. Knopf, 1979 (June 2000 Printing)

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About This Page

This page has been put together by a college student as a project for my Mineralogy course, http://www.emporia.edu/earthsci/amber/go336/, from Emporia State University, http://www.emporia.edu. Please feel free to e-mail me at ashleyj61@hotmail.com. This page was created on April 12, 2001.

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copyright 2001 © Josh Ashley All rights reserved.